Launch of the Cygnus spacecraft was supposed to be the start of the third of Orbital Science Corporation’s eight NASA-contracted resupply missions to the International Space Station. Instead, Orbital and NASA are left picking up this pieces today after the company’s Antares rocket erupted into a roiling ball of fire after liftoff that consumed the vehicle and its launch pad, leaving stunned observers young and old shaken and in shocked disbelief.
“It is far too early to know the details of what happened,” said Mr. Frank Culbertson, Orbital’s Executive Vice President and General Manager of its Advanced Programs Group.“As we begin to gather information, our primary concern lies with the ongoing safety and security of those involved in our response and recovery operations. We will conduct a thorough investigation immediately to determine the cause of this failure and what steps can be taken to avoid a repeat of this incident. As soon as we understand the cause we will begin the necessary work to return to flight to support our customers and the nation’s space program.”
Early analysis points to trouble within the rocket’s first stage propulsion system which is powered by twin Aerojet AJ-26 engines. The AJ-26’s are refurbished Russian NK-33 engines originally built in the 1960’s for the N-1 launch vehicle, the Soviet Union’s attempt at a counterpart to NASA’s Saturn V during the race to land humans on the Moon. The N-1 first stage failed in all three of its launch attempts and caused significant loss of life and resources and cost the USSR the Moon Race.
Loss of the Orb-3 mission cast a pall of uncertainty over the future of Orbital’s Antares launch vehicle as well as adding significant challenges for the company still under contract with NASA to deliver another five Cygnus cargo craft to the space station over the next three years.
After the mishap, NASA officials were quick to emphasize that the International Space Station is not at risk of facing a supply shortage or a reduction in crew size.
“While NASA is disappointed that Orbital Sciences’ third contracted resupply mission to the International Space Station was not successful today, we will continue to move forward toward the next attempt once we fully understand today’s mishap,” said William Gerstenmaier, Associate Administrator of NASA’s Human Exploration and Operations Directorate. “The crew of the International Space Station is in no danger of running out of food or other critical supplies.”
“Orbital has demonstrated extraordinary capabilities in its first two missions to the station earlier this year, and we know they can replicate that success. Launching rockets is an incredibly difficult undertaking, and we learn from each success and each setback. Today’s launch attempt will not deter us from our work to expand our already successful capability to launch cargo from American shores to the International Space Station.”
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Antares was originally scheduled to launch on October 27, but was delayed 24 hours by a sailboat the strayed into the launch hazard zone. Repeated attempts to hail the boat, even using aircraft to buzz it at low altitude, failed to raise a response from the occupants, who had presumably turned their radio off and were unaware of the impending launch.
After the “boatergate” incident, as it briefly became known on social media, the rocket was de-tanked and preparations made for a second attempt. As during the previous day, Antares breezed through the countdown with no technical issues. The only concern was a different kind of breeze, vigorous upper-level winds that threatened to exceed acceptable limits.
However, right on time at 6:22 pm EDT, the Antares Aerojet AJ-26 powered first stage thundered to life, lofting Orbital’s third Commercial Resupply Services mission into the evening sky on its terrifyingly brief flight.
Armageddon Over The Island
According to video analysis and telemetry, approximately 8 seconds after launch, a liquid oxygen turbopump on the rocket’s north-side engine failed, sending a stream of dark brown kerosene-rich exhaust pouring down on the launch pad. Seconds later, the bottom of the rocket blew apart, sending debris flying through the air as Antares paused in the sky, then fell back to Earth.
Before it impacted the ground, Wallops’ Range Safety Officer triggered the Flight Termination System to ensure the rocket, potentially with one first stage engine and an undamaged, armed solid fuel second stage, would not pose a danger to the public who were watching from as close as less than two miles away.
Antares smashed itself back onto the launch complex, mere feet to the north of where it lifted off seconds earlier, and erupted into a massive ball of flame and debris. Almost too fast for observers to realize what had happened, a terrifyingly loud blast concussion rolled over the press and public viewing areas as safety personnel rushed to evacuate those areas in case toxic fumes drifted their way.
Less than twenty seconds after launch, it was over.
All that remained of Orb-3 was flaming debris, bits of payload scattered about the area and surrounding beach, and the hollowed out, scorched shell of Cygnus, which landed upright (or upside down) in a pit next to the impact point feet from the liquid oxygen tank farm. A giant 30-40 foot wide crater marked the rocket’s explosion literally right next to its launch pad. The pad itself appeared to have narrowly escaped being destroyed.
Fire and security personnel rushed to the scene, but with damage limited to the immediate area around the launch complex and thousands of gallons of burning kerosene fuel, the decision was made to let the fires burn out overnight.
At the time of writing this article, a secure zone has been established and access prohibited until emergency workers determine the area is safe to enter. An aerial survey will provide the first detailed views of the battered launch complex.
(Editor’s Note: The following is an update posted by Orbital this morning after the aerial survey )
“Early this morning, range officials performed an aerial survey of the launch facilities and surrounding areas at NASA’s Wallops Flight Facility where yesterday’s failure of the Antares rocket occurred after it lifted off from the Mid-Atlantic Regional Spaceport’s Pad 0A. Shortly after, a team of representatives from NASA, MARS and Orbital entered the launch site to perform a preliminary assessment of the launch complex and related facilities. The overall findings indicate the major elements of the launch complex infrastructure, such as the pad and fuel tanks, avoided serious damage, although some repairs will be necessary. However, until the facility is inspected in greater detail in the coming days, the full extent of necessary repairs or how long they will take to accomplish will not be known.”
“NASA has posted aerial views of the launch pad taken earlier today here.”
“Also today, Orbital made progress forming a permanent Accident Investigation Board (AIB) comprised of company officials, along with representatives from NASA and the NTSB, with the FAA providing overall oversight of the process. Initially, Mr. Rich Straka, Senior Vice President and Deputy General Manager of Orbital’s Launch Systems Group, served as the interim chairman to begin the investigation process immediately after the launch mishap. Today, Orbital appointed Mr. Dave Steffy, Senior Vice President and Chief Engineer of the company’s Advanced Programs Group, a highly experienced engineer well-versed in launch vehicle engineering and operations, to serve as the permanent chairman of the AIB.”
The Cursed Engine
While it is too soon to issue a blanket condemnation of the 40 year-old Russian-built NK-33 engines which Aerojet refurbished, certified and christened the AJ-26, it would be remiss to leave out mention of the NK-33’s troubled past.
NK-33 was originally developed for the Soviet Union’s secret N1 rocket in the 1960’s and early 1970’s. The N1 was the Soviet answer to the American Saturn V and their hope to beat the United States in landing people on the Moon first.
From the outset, troubles plagued the NK-33. The engine uses a highly-advanced “closed-loop” oxygen combustion cycle that heats up liquid oxygen oxidizer and uses it to drive the powerplant’s turbopumps. The heated oxygen is then cycled back into the engine for combustion. Closed-loop cycle is so advanced, and difficult to perfect, that von Braun and his team discarded it as an option and, in fact, no American rocket engine manufacturer has ever attempted to build a large liquid propellant engine using this scheme.
However, the efficiency of a closed-loop cycle engine can be 30% higher than a conventional engine of the same size. This was essential for the Soviet designers because while the U.S. had the capability to manufacture the massive 1.5 million pound F-1 engine for the Saturn V, the USSR had no capability to build engines of that scale.
Their only option was to cluster many smaller engines and make the engines as efficient as possible. In fact, the NK-33 was the most efficient hydrocarbon (kerosene) burning liquid fuel engine ever developed until SpaceX developed the Merlin.
The NK-33 had only one fundamental problem: it kept blowing up.
The thermal stresses of the close-loop design proved to be insurmountable. Three test launches of the rocket were attempted. The first exploded immediately after liftoff and none reached first stage shutdown. The turbopumps kept flying apart. Debris fouled the systems and essentially, the engine was too much for the engineers to control.
Fast-forward 40 years. The AJ-26 has improved systems, including pumps. It is an upgraded version of the NK-33 that utilizes modern processes, metals and computer-aided design. The cursed engine had supposedly been tamed.
And then pumps started coming apart. In one test earlier this year, an AJ-26 came apart on the test stand at Stennis Space Center. In the words of an official at Orbital, the pump “flew apart”.
After an intensive investigation, Aerojet was unable to determine the root cause of the failure. Absent a “smoking gun”, they thoroughly inspected the engines used on the ill-fated Orb-3 launch and declared that they appeared to be in good shape.
Appearances seem to have been deceiving, which leaves Orbital and Aerojet with a multi-million dollar loss and wondering what the future holds for Antares and its allegedly cursed engine.
Payloads and Dreams Lost
Orbital’s third contracted cargo resupply mission with NASA to ISS was to deliver almost 5,000 pounds of science and research, crew supplies, vehicle hardware and spacewalk tools to the orbital complex and its crew. The scientific investigations carried by Cygnus were designed to enable the first space-based observations of meteors entering Earth’s atmosphere, help determine how blood flows from the brain to the heart in the absence of gravity and investigate the impact of space travel on both the human immune system and an individual’s microbiome, the collection of microbes that live in and on the human body. In December, after more than a month at ISS and loaded with 3,000 pounds of rubbish, the space station crew would have unberthed it from the Harmony module for a fiery re-entry into Earth’s atmosphere.
A number of secondary payloads and 18 cubesats were also part of Cygnus’ manifest. Of note, the spacecraft carried a group of 18 student-led investigations, collectively part of the Yankee Clipper suite of research under the Student Spaceflight Experiments Program (SSEP). The studies would have investigated a range of topics from a crystal growth study that will enable students to learn more about how fluids act and form into crystals in the absence of gravity to how microgravity affect milk spoilage. Yankee Clipper is the eighth flight opportunity associated with the SSEP, an initiative of the National Center for Earth and Space Science Education in partnership with NanoRacks.
Instead of scientific learning, Antares dramatic explosion left the students, shaken and many in tears, to learn a life lesson in disappointment and failure when everything had seemed to be going right.
Spaceflight Is Not “Routine”
Orb-3 was planned as a fairly standard ISS cargo run Antares was to have launched Cygnus into orbit in a nine and half minute ascent from Pad 0A at Wallops Island. After separation from Antares, Cygnus would deploy its solar arrays and prepare its propulsion system for maneuvers. Thruster firings would then increase its altitude, moving closer to the space station. Diuring a nominal mission, the Cygnus team conducts a series of tests to ensure the spacecraft’s readiness for rendezvous and berthing with the space station.
On Flight Day 2, Cygnus would move closer to orbital laboratory, eventually loitering at the same altitude as the space station, 1,000 to 2,000 kilometers behind it. Finally, on November 2, NASA would have hopefully provided a “go” for Cygnus to berth with the station. After approach to within 39.4 feet of the station, Cygnus would have been commanded to “free drift” by the astronauts aboard the station, captured by the robotic arm and subsequently attached to the station. On December 2, Cygnus would be released from the station and after additional free-flying investigations of its capabilities, would fire its thrusters one last time to send it hurtling back into the atmosphere and a flaming destruction.
Antares is the largest launch vehicle in Orbital Sciences’ fleet. It is also the first large liquid fuel rocket to fly from Wallops Island. Antares is a two-stage launch vehicle consisting of a liquid-fueled liquid Oxygen/refined kerosene first stage powered by two Aerojet Rocketdyne AJ26 engines. The second stage is an ATK CASTOR 30XL solid motor. Antares employs a 32.5 ft. (9.9 meter) fairing to protect Cygnus from atmospheric heating as it accelerates through Earth’s atmosphere.
Antares is capable of supporting mid-inclination and polar orbiting spacecraft weighing up to approximately 13,500 lb. (6123 kg) and 5,500 lb. (2495 kg), respectively. The standard range of orbital inclination from the Virginia launch site is 38 to 60 degrees, which makes it as effective as Kennedy Space Center for launches to the International Space Station which flies in an orbit inclined 51.6 degrees to Earth’s equator.
Cygnus is a free-flying spacecraft developed under NASA’s Commercial Orbital Transportation program. The spacecraft consists of a Pressurized Cargo Module (PCM) and a Service Module (SM). The PCM carries pressurized cargo and experiments to the space station and pressurized disposal cargo away from the station for destructive re-entry at the end of the mission. The SM provides power, propulsion, guidance, computation, and communications for Cygnus.
Developed by Thales Alenia of Turin, Italy, the PCM shares its heritage with numerous space station modules, including the Multipurpose Logistics Module, the Autonomous Transfer Vehicle, and Nodes 2 and 3. The Cargo Module is designed with two configurations. The standard configuration carries up to 4,409 lbs. (2,000 kg) of cargo while the enhanced variant will carry up to 5,952 lbs. (2,700 kg). The Orbital CRS-3 mission will use the standard configuration.
For on-orbit maneuvering, rendezvous operations and re-entry. Cygnus’ Service Module contains a dual-mode N2H4/MON-3 or N2H4, IHI Delta V engine generating 100 pounds of thrust and 32 Rocket Engine Assemblies (REAs) which provide 6 pounds of thrust, each.